Coexistence of Candida albicans and Enterococcus faecalis increases biofilm virulence and periapical lesions in rats.

The present study utilized an in vitro dual-species biofilm model and an in vivo rat post-treatment endodontic disease (PTED) model to investigate whether co-infection of Candida albicans and Enterococcus faecalis would aggravate periapical lesions. The results showed that co-culturing yielded a thicker and denser biofilm more tolerant to detrimental stresses compared with the mono-species biofilm, such as a starvation-alkalinity environment, mechanical shear force and bactericidal chemicals. Consistently, co-inoculation of E. faecalis and C. albicans significantly increased the extent of in vivo periapical lesions compared with mono-species infection. Specifically, coexistence of both microorganisms increased osteoclastic bone resorption and suppressed osteoblastic bone formation. The synergistic effects also up-regulated inflammatory cytokines including TNF-α and IL-6. In summary, coexistence of C. albicans and E. faecalis increased periapical lesions by enhanced biofilm virulence.

Mechano-chemical coupling of irrigation enhances endodontic biofilm debridement.

The complexity of the root canal system results in areas where mechanical instrumentation is impossible during endodontic treatment. To disinfect these areas, the effect of irrigation on biofilm debridement is of great significance but has not yet been well explored. Using an in vitro Enterococcus faecalis biofilm model and a biofilm reactor, the present study provides a better understanding of the relative contributions of mechanical and chemical effects of irrigation on biofilm removal, as well as the factors influencing their coupling efficiency. The results clearly demonstrate that, the mechanical effect of irrigation alone does not significantly influence the stability of biofilms. However, the mechanical effect promotes biofilm eradication by coupling with the chemical effect. In addition, both the irrigant concentration and the irrigant-biofilm contact time are among the key factors affecting the mechano-chemical coupling. This knowledge may serve to better direct endodontists in designing irrigation regimes during root canal therapy.

Bioceramic Materials and the Changing Concepts in Vital Pulp Therapy.

Vital pulp therapy (VPT) is devised to preserve and maintain vitality of pulpally involved teeth challenged by a variety of intraoral conditions. Notable progress has been made in this field due to a better understanding of pulp physiology, improved clinical protocols and advanced bioceramic materials paired with adhesive technology. With focused case selection, conservative VPT can provide reliable treatment options for permanent teeth diagnosed with normal pulps or reversible pulpitis.

Broken Instrument Removal from Mandibular First Molar with Conebeam Computed Tomography based Pre-operative Computer-assisted Simulation: A Case Report.

Intracanal separation of nickel titanium files hinders complete shaping, cleaning, and filling of the root canal system and ultimately influences the endodontic treatment outcome. In this case report, we presented a successful broken instrument retrieval from the middle third of the mesiobuccal root canal of tooth #30 with the assistance of cone-beam computed tomograpgy based preoperative computer-assisted simulation, micro-trepan bur and micro-tube from Micro-Retrieve & Repair system and dental operative microscope. The involved tooth was then successfully cleaned, shaped and obturated followed by coronal restoration. At the three-year follow-up, tooth #30 was asymptomatic and functioned well without radiographic changes. The present case provides an example to show the robustness of computer-assisted technology in dental procedures and to show how the combination of advanced techniques can facilitate root canal therapy.

Dentists Are at a Higher Risk for Oral Helicobacter pylori Infection.

Oral cavity has been taken as one of the major reservoirs for Helicobacter pylori, the bacteria responsible for gastric infection and cancers. Dentists are frequently exposed to saliva; thus, theoretically, they are at a higher risk for oral H. pylori infection. In the present study, to test this hypothesis and to find out the potential factors associated with the increased risk, a cross-sectional study was carried out on a large scale of dentists (N = 90) and nondentist controls (N = 110). By using nested polymerase chain reaction to amplify a specific DNA fragment of H. pylori, we found 7.27% of saliva samples from the nondentist group and 16.67% of saliva samples from the dentist group were oral H. pylori positive, and the difference between groups was statistically significant (χ 2 = 4.292, p = 0.038). Importantly, however, after stratifying enrolled subjects with factors which might interfere with the comparison of H. pylori detection rate between groups, we still observed a higher H. pylori frequency in the dentists than that in the controls in subgroups, including those with good individual hygiene, healthy lifestyle, and physical condition, as well as those living with families to be gastric disease free and not sharing meals with H. pylori-positive persons, respectively. Moreover, the frequency of clinical practice per week of the investigated dentists was closely associated with an oral H. pylori infection risk. Our data indicates that dentists are at a higher risk for H. pylori infection, and intensive attention needs to be paid on this issue.

Sucrose promotes caries progression by disrupting the microecological balance in oral biofilms: an in vitro study.

Sucrose has long been regarded as the most cariogenic carbohydrate. However, why sucrose causes severer dental caries than other sugars is largely unknown. Considering that caries is a polymicrobial infection resulting from dysbiosis of oral biofilms, we hypothesized that sucrose can introduce a microbiota imbalance favoring caries to a greater degree than other sugars. To test this hypothesis, an in vitro saliva-derived multispecies biofilm model was established, and by comparing caries lesions on enamel blocks cocultured with biofilms treated with sucrose, glucose and lactose, we confirmed that this model can reproduce the in vivo finding that sucrose has the strongest cariogenic potential. In parallel, compared to a control treatment, sucrose treatment led to significant changes within the microbial structure and assembly of oral microflora, while no significant difference was detected between the lactose/glucose treatment group and the control. Specifically, sucrose supplementation disrupted the homeostasis between acid-producing and alkali-producing bacteria. Consistent with microbial dysbiosis, we observed the most significant disequilibrium between acid and alkali metabolism in sucrose-treated biofilms. Taken together, our data indicate that the cariogenicity of sugars is closely related to their ability to regulate the oral microecology. These findings advance our understanding of caries etiology from an ecological perspective.

Revascularization-associated Intracanal Calcification: Assessment of Prevalence and Contributing Factors.

INTRODUCTION: Intracanal calcifications have been reported in endodontic cases after revascularization. The purpose of the current study was to determine the incidence of intracanal calcification and potential contributing factors in retrospective revascularization cases. METHODS: Among 37 patients who had undergone revascularization between 2010 and 2014, 29 cases were assessed with average follow-up period of 24.9 months. Clinical and radiographic examinations were performed to evaluate the treatment outcomes, eg, resolution of apical periodontitis (AP), root development, and occurrence of intracanal calcification. Radiographic assessment revealed varied calcification patterns, which were classified into calcific barrier or canal obliteration, collectively referred to as revascularization-associated intracanal calcification (RAIC). RESULTS: All 29 cases demonstrated resolution of AP, whereas continued root development with apical closure occurred in 23 of 29 cases (79.3%). RAIC was noted in 18 of 29 cases (62.1%), among which 5 of 18 cases (27.8%) were classified as calcific barrier and 13 of 18 cases as canal obliteration (72.2%). Higher frequency of RAIC was noted in the cases with induced bleeding (16 of 23 cases, 69.6%), whereas the 6 cases without induced bleeding showed RAIC at 33.4%. Also, RAIC occurred more frequently in cases medicated with Ca(OH)2 (10 of 13 cases, 76.9%) than in those medicated with antibiotic pastes (6 of 13 cases, 46.2%). CONCLUSIONS: This study indicated that RAIC is common (62.1%) among cases treated with revascularization. Multiple contributing factors may include the type of medicaments and induction of intracanal bleeding. Although RAIC does not interfere with resolution of AP, some cases may progress to complete obliteration of root canals and would impede normal function of dental pulp tissues.

The oral microbiome diversity and its relation to human diseases.

As one of the most clinically relevant human habitats, the human mouth is colonized by a set of microorganisms, including bacteria, archaea, fungi, and viruses. Increasing evidence has supported that these microbiota contribute to the two commonest oral diseases of man (dental caries and periodontal diseases), presenting significant risk factors to human health conditions, such as tumor, diabetes mellitus, cardiovascular diseases, bacteremia, preterm birth, and low birth weight in infants. It is widely accepted that oral microorganisms cause diseases mainly by a synergistic or cooperative way, and the interspecies interactions within the oral community play a crucial role in determining whether oral microbiota elicit diseases or not. Since a comprehensive understanding of the complex interspecies interactions within a community needs the knowledge of its endogenous residents, a plenty of research have been carried out to explore the oral microbial diversity. In this review, we focus on the recent progress in this field, including the oral microbiome composition and its association with human diseases.

[Human buccal mucosa microbiota succession across age].

OBJECTIVE: This investigation aimed to examine how buccal mucosa microbiome succeeds in a healthy population with different ages and dentition stages. METHODS: Twenty-five subjects were recruited and subdivided into five groups: primary dentition group, mixed dentition group, adolescent group, adult group, and elderly group. Individual mucosal microbiota was obtained by gently scraping both sides of the buccal mucosa with a cotton swab. Microbial diversity was analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). RESULTS: 1) The composition of buccal mucosa microbiota has great intra-individual divergence. 2) The average band numbers of the primary dentition group, mixed dentition group, adolescent group, adult group, and elderly group were 21.2 +/- 4.0, 17.8 +/- 3.9, 15.8 +/- 4.3, 16.8 +/- 3.7, and 22.2 +/- 6.5, respectively. No between-group differences was observed (P > 0.05), indicating that predominant strains in the oral cavity may be stable throughout an individual's lifetime. 3) The Shannon indices of primary dentition group, mixed dentition group, adolescent group, adult group, and elderly group were 1.73 +/- 10.2, 1.43 +/- 0.1, 1.05 +/- 0.2, 1.45 +/- 0.2, and 1.63 +/- 0.3, respectively. A significant between-group difference was observed (P = 0.003), indicating that the microbial diversity of the buccal mucosa decreases from childhood through adolescence, but increases from adult through senescence. 4) The clustering analysis showed that most of the samples in the same group clustered together, indicating higher intra-group community structure similarity. CONCLUSION: Composition of the buccal mucosa microbiota was different among age groups. Adolescence may be an essential turning point of microbial ecology succession throughout life.

Effects of ginkgoneolic acid on the growth, acidogenicity, adherence, and biofilm of Streptococcus mutans in vitro.

Ginkgo biloba has long been used in traditional Chinese medicine. In this study, ginkgoneolic acid, a kind of compound extracted from G. biloba, was investigated for its effects on growth, acid production, adherence, biofilm formation, and biofilm morphology of Streptococcus mutans. The results showed that ginkgoneolic acid inhibited not only the growth of S. mutans planktonic cells at minimum inhibitory concentration (MIC) of 4 µg/mL and minimum bactericidal concentration (MBC) of 8 µg/mL but also the acid production and adherence to saliva-coated hydroxyapatite of S. mutans at sub-MIC concentration. In addition, this agent was effective in inhibiting the biofilm formation of S. mutans (MBIC(50) = 4 µg/mL), and it reduced 1-day-developed biofilm of S. mutans by 50 % or more at low concentration (MBRC(50) = 32 µg/mL). Furthermore, the present study demonstrated that ginkgoneolic acid disrupted biofilm integrity effectively. These findings suggest that ginkgoneolic acid is a natural anticariogenic agent in that it exhibits antimicrobial activity against S. mutans and suppresses the specific virulence factors associated with its cariogenicity.

[New progress in research of Granulicatella species].

Granulicatella species are facultative anaerobic, catalase-negative Gram-positive cocci, oral microbiome researches find out Granulicatella species are dominant bacteria in oral cavity which may cause opportunistic infection like periodontal disease, endodontic infection. This review summarized research progress of Granulicatella species.